I think teacher would prefer to keep things at minimal and only the necessity to avoid lost of items as they have a lot of children's belonging to care for. Sturdy name labels( that doesnt comes off) would make everything easier to track and identify. Wet bags will be better as to compare with ziploc bags. Pack the clean set of clothes with towel and diaper to change after shower in wetbag and usually tchrs will use the same bag to put in the soiled clothes and towel. Wetbags with 2 compartment will help separate the wet towel and the soiled clothes. Do clarify with the school teacher to avoid any confusion. Towels use microfiber towel as those are soft and will not cause any red patches when patting dry ur child skin especially after shower their skin are more supple i would say. Anti slips are not 100% fall proof, if really need to wear find ones tht has the most anti slip and if the your child is doing physical activities i would advice teacher to remove them. It will minimize the chances of getting into falls and accidents. Fresh milk check with school if the have separate fridge to keep the milk in if not in my opinion i rather have formula milk instead unless you dont mind fresh milk to be kept together with the school kitchen groceries. Maybe you can pack the fresh milk in an airtight containers or bag. Hope these would help you. Cheers and all the best !
Hope it helps
An Lela Liyah